.22 Caliber rimfire adapter system for M16 type rifle

Abstract

A unitary bolt and chamber adapter for field replacement, without tools, of the conventional bolt assembly of rifles of the type M16 and AR-15 provides for the use of conventional .22 caliber long rifle rimfire ammunition in the rifle instead of the larger conventional centerfire ammunition. The bolt functions in semiautomatic fire by conventional blowback action. Through cooperation with an improved .22 caliber rimfire magazine adapter, the breech automatically remains open after firing the last round from the magazine. The bolt guide rails are flexibly attached to the chamber providing for reliable operation in a larger number of rifles. A spring actuated forward locator on the bolt assembly keeps the adapter seated in the rifle chamber, compensating for differences in gun receiver lengths. An undercut bolt face provides the positive extraction of a double extractor system with a single extractor, and a groove-and-land chamber adapter provides reliable operation with good and poor quality ammunition. A gas diverter protects the rifleman's eyes and provides a clean receiver without modifying the original gun.

I claim: 
     
       1. A rimmed cartridge extractor system for the bolt face of a rifle comprising: a. a hooked lever arm extractor;   b. a case rim retainer positioned on the bolt face approximately opposite the said lever arm extractor; and   c. an undercut of approximately twenty degrees in the said rim retainer.   
     
     
       2. The extractor system as claimed in claim 1 wherein the said case rim retainer is recessed in the bolt face and the said undercut extends over approximately a 90° segment of the said rim retainer.